The technology for making the information coded as bit data and an electronic document correlate and unify within a printed document is known well.
The concept of 1-dimensional or 2-dimensional barcodes and the usage for acquiring the positional information on a document based on the information added to the printed document is disclosed (refer to Patent References 1-8, for example).
An invention which unifies barcodes of different dimensions is also disclosed (for example, Patent Reference 9). As a specific example, a digital information carrier wherein 1-dimensional and 2-dimensional layers are unified is shown there.
A barcode of 1-dimensional and 2-dimensional layers having a multilayer structure is also disclosed (for example, Patent References 10 and 11).
It is also disclosed how to integrate a barcode in an image or a secret document (for example, Patent References 12-19).
A data coding method performed using an illustration symbol is also disclosed (for example, Patent References 20 and 21).
A method for coding by using at least two sorts of symbols and arranging these symbols in a matrix shape on various media wherein a document display is possible (for example, Patent Reference 22) is also disclosed. As a specific example it is shown how to use a monochrome lattice-like pattern.
The method of combining a plurality of 2-dimensional dot codes using different colors is also disclosed (for example, Patent References 23-26).
Dot Code
A technology based on a self-synchronous type of symbols called “glyphs” is also disclosed (for example, Non-Patent Literature 1). It is indicated that glyph positions provide for the glyph clocking mechanism, and that glyph orientations provide for information to be digitally encoded.
In addition, a method for showing positional information using glyphs over the whole predetermined region of a document is also disclosed (for example, Patent Reference 27). It is indicated that each glyph is shown by a line segment inclined to the left or to the right that provides for 1 bit of information. Furthermore, other glyphs which can code 2 bits of data are disclosed (for example, Patent Reference 28). It is indicated that such glyphs are expressed in a triangular shape and have four different directions, this providing for 2 bits of information per glyph.
[Patent Reference 1] U.S. patent application publication Ser. No. 20020027165
[Patent Reference 2] U.S. Pat. No. 6,418,244 B2
[Patent Reference 3] U.S. Pat. No. 6,176,427 B1
[Patent Reference 4] U.S. Pat. No. 5,617,358
[Patent Reference 5] U.S. Pat. No. 6,070,805
[Patent Reference 6] U.S. Pat. No. 5,742,041
[Patent Reference 7] U.S. Pat. No. 6,043,899
[Patent Reference 8] JP Patent Application Publication Heisei 7-306904
[Patent Reference 9] U.S. Pat. No. 006,398,117
[Patent Reference 10] JP Translation of PCT International Application WO 96/18972
[Patent Reference 11] U.S. Pat. No. 5,525,798
[Patent Reference 12] U.S. Pat. No. 5,525,798
[Patent Reference 13] U.S. Pat. No. 6,256,398 B1
[Patent Reference 14] U.S. Pat. No. 05,522,623 A
[Patent Reference 15] U.S. patent application publication Ser. No. 20020060396
[Patent Reference 16] EP Patent No. 1154373 A2
[Patent Reference 17] JP Patent Application Publication 2001-320573
[Patent Reference 18] JP Patent Application Publication 2002-36763
[Patent Reference 19] JP Patent Application Publication 2002-63142
[Patent Reference 20] FR Patent No. 2809210 A1
[Patent Reference 21] U.S. Pat. No. 6,460,766 B1
[Patent Reference 22] U.S. Pat. No. 6,273,340 B1
[Patent Reference 23] EP Patent No. 1178428 A1
[Patent Reference 24] JP Patent Application Publication 2000-293644
[Patent Reference 25] JP Patent Application Publication 2000-293645
[Patent Reference 26] JP Patent Application Publication 2000-293646
[Patent Reference 27] U.S. Pat. No. 6,327,395 B1
[Patent Reference 28] U.S. Pat. No. 5,245,165
[Non-Patent Literature 1] Hecht D., Printed Embedded Data Graphical User Interfaces, Computer, March 2001, pp. 47-55